滨里海盆地东缘北特鲁瓦地区白云岩特征及其储层发育机制

白云岩是滨里海盆地盐下石炭系碳酸盐岩的重要储层类型。在岩芯、薄片、物性与地球化学等资料分析的基础上，对研究区KT-Ⅰ油组的白云岩类型与储集性能进行了分析，并探讨了其储层发育的控制因素与模式。结果表明，白云岩类型与其储集物性具有较明显的相关性，以生屑铸模孔及溶蚀扩大孔为主的残余生屑白云岩物性与含油气性最好，以晶间（溶）孔为主的粉细晶白云岩和以生屑铸模孔及晶间孔为主的泥粉晶白云岩次之，而以晶间微孔为主的泥晶白云岩最差，难以成为有效储层。原生孔隙发育的相对高能生屑滩环境是该区优质白云岩储层发育的相带基础。晚石炭世准同生期大气淡水溶蚀作用与以渗透回流白云化（白云石有序度分布于0.32～0.67，δ13C介于-0.22‰～5.94‰，δ18O介于-1.09‰～2.45‰）为主的早期白云化作用为白云岩储层早期孔隙的发育与保存奠定了坚实的基础；早二叠世以来埋藏期各类裂缝的发育及酸性流体的溶蚀作用则对储层的晚期扩孔改造至关重要。

Characteristics and Development Mechanism of Dolomite Reservoirs in North Truva of Eastern Pre-Caspian Basin

Dolostone is a significant reservoir type of pre-salt Carboniferous carbonate rocks in Pre-Caspian Basin. Based on the analysis of core, thin section, petrophysical properties, geochemical data and other related data, reservoir classification and performance of dolostones in KT-Ⅰ Formation were analysed, and their controlling factors and development models were also investigated. The results show that types of dolostones have a significant influence on their petrophysical properties. Among all the types, reservoir property and oil richness of residual bioclast dolostone mainly with moldic pore and dissolution enlarged pores is the best, that of silt to fine crystalline dolostone mainly with intercrystal pore and its dissolution pore is medium, as well as mud to silt crystalline dolostone mainly with moldic pore and intercrystal pore, but mud crystalline dolostone mainly with intercrystal micropore is poor on reservoir property. Bioclast shoal with more primary porosity formed in the relatively high hydrodynamic environment is favorable for dolomite reservoir formation of high quality. Penecontemporaneous dissolution of fresh water and early dolomitization mainly via seepage-reflux dolomitization (dolomite order degree falls in between 0.32 and 0.67, δ13C ranges from -0.22‰ to 5.94‰ and δ18O ranges from -1.09‰ to 2.45‰) before massive compaction have a dominant effct on early porosity formation and preservation for dolomite reservoir in the Late Carboniferous. At the burial diagenesis stage the formation of fractures with different causes and dissolution of acidic fluids are the vital factors for further porosity increasement of dolomite reservoir since the Early Permian.